Influenza, commonly known as flu, is an infectious disease caused by a virus. In a human, symptoms of infection include: fever, sore throat, muscle pain, headache, and fatigue. In serious cases, influenza can cause pneumonia which can be fatal to weak individuals. Influenza is more severe than the common cold with symptoms sometimes lasting more than a week and is caused by a different virus. Although influenza can produce nausea and vomiting, these symptoms are more characteristic of gastroenteritis, an unrelated illness sometimes called “stomach flu.”
Influenza is spread through the air by coughing or sneezing. Influenza can also be transmitted through contact with body fluids on contaminated surfaces. Influenza viruses can survive for several days at room temperature and indefinitely at low temperatures.
Minimizing contact with infected individuals prevents the spread of influenza. People who contract influenza are most infective between the second and fourteenth days after infection. Children are more infectious than adults, shedding the influenza virus at a higher rate.
Vaccinations are given to weak individuals like children and the elderly to minimize the risk of influenza infection. The most common vaccine contains inactivated material from three viruses. Unfortunately, vaccines formulated for one year can be ineffective the next since influenza viruses rapidly mutate. Thus, it is possible to get vaccinated and still get influenza.
Vaccines can cause general infection symptoms to appear, though these symptoms are usually not as severe or as long-lasting as influenza. The most dangerous side-effect of vaccination is a severe allergic reaction; however, these reactions are rare.
People with influenza are advised to get plenty of rest, drink lots of liquids, avoid using alcohol and tobacco and, if necessary, take medications such as acetaminophen to relieve fever and muscle aches. Since influenza is caused by a virus, antibiotics have no effect; unless prescribed for secondary infections such as pneumonia. Antiviral medications are sometimes effective, but viruses can develop resistance to them.
Antiviral drugs are designed to halt the spread of the virus in the body and must be taken within a few days of the onset of influenza symptoms. Different strains of influenza virus have differing degrees of resistance against these antivirals and it is impossible to predict what degree of resistance a future pandemic strain might have.
Over the counter medicines are taken to relieve influenza symptoms, but they do not affect the virus. Analgesics reduce fever, aches, pains, sinus pressure, and sore throat. Cough suppressants get rid of coughs. Also, antihistamines and decongestants minimize nasal congestion, runny nose, watery eyes, and cough. Finally, sore throats are knocked out with local anesthetics.
Homeopathic and other cold and flu remedies that fail to meet the regulatory requirements as drugs that treat disease, or the standards of evidence-based medicine, are sold as nutritional supplements. They may be based on extracts of living things, but may lack documentation of their safety and effectiveness. They may be promoted by those who deny the need for such testing and may fail to provide a scientifically plausible rationale for their effectiveness.